The invention described herein may be manufactured, used, and licensed by or for the U.S. Government for government purposes.
The present invention relates to a monitor for alerting those responsible for the care of individuals to the onset of anomalous physical activity. More particularly the invention relates to a monitor responsive to anomalous activity while distinguishing the same from casual activity associated with normal quiet daytime activities.
The problem of alerting caregivers to the onset of distress or to a medical disorder such as a seizure has always existed. The specific problem is to alert those responsible for the care of individuals to the onset of anomalous physical activity and to distinguish this type of activity from normal casual motion. The anomalous physical activity ranges from that associated from distress while sleeping to that associated with certain medical disorders such as epilepsy. The individual may suffer from a condition where prompt detection and enhanced accuracy in documentation of medical episodes is required to assist in improving care. The device would have great benefit for parents, teachers and other caregivers who cannot continuously and visually monitor the individual in their care. It would be a great benefit of having a monitor useful in the home or in group environments such as a classroom of students with special needs.
Caregivers of individuals afflicted with certain illnesses or conditions such as epilepsy are required to closely and continuously monitor those under their care. This is also the case for parents concerned with restless activity in their children during sleeping hours. U.S. Pat. Nos. 5,523,742, 5,610,590, and 5,879,309 describe monitors developed to address these problems.
Continuous visual monitoring of individuals is usually impossible and periodic monitoring is often insufficient. The monitors described in U.S. Pat. Nos. 5,523,742 and 5,610,590 provide relief during sleeping hours, but are inappropriate for reliably discriminating seizures from the casual activity associated with normal quiet daytime activities. The use of either of these monitors would produce an unacceptably high false alarm rate resulting in undue anxiety and, perhaps, even a loss of faith in the device. The monitor described in U.S. Pat. No. 5,879,309 employs a custom made sensor that is not 5 commercially available and is costly to produce. The sensor used in U.S. Pat. No. 5,879,309 also has a highly nonlinear response that does not allow optimal adjustments of monitor sensitivity. It also lacks the sensitivity to respond to low amplitude motion that is characteristic of certain types of disorders.
Accordingly, one object of the present invention is to provide a sensor that is sensitive to respond to low amplitude motion.
Another object of this invention is to provide a monitor device that minimizes false alarms due to reading, walking or related casual activities.
A specific object of this invention is to provide a monitor device that uses a new, commercially available sensor having a linear, omnidirectional response with high sensitivity, ultra-low power consumption, low cost, and small size.
Other objects will appear hereinafter.
It has now been discovered that the above and other objects of the present invention may be accomplished in the following manner.
Specifically, the present invention comprises a monitor device for monitoring the activity of an individual to provide an alarm for anomalous by the individual. The device incorporates a new, commercially available sensor having desired features of linear, omnidirectional response, high sensitivity, ultra-low power consumption, low cost and small size.
Also included in the monitor device of the present invention is interface electronics for receiving the voltage outputs and buffering the voltage outputs to generate a first reference voltage for each axis of the accelerometer. Each voltage output is amplified and compared to a first reference voltage to produce a digital signal.
A microcontroller compares the digital signal to an adjustable second reference voltage. The microcontroller discriminates between normal activity and anomalous activity by identifying sensor activity within sequences of preselected time intervals and sending an alarm signal upon detection of the anomalous activity. An alarm for receiving the alarm signal and signaling an alarm completes the device.